In a triangle ABC,if 2r_1 = 3r_2 = r_3,then a | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(A) We know that the exradii of a triangle are given by $r_1 = \frac{\Delta}{s-a}$,$r_2 = \frac{\Delta}{s-b}$,and $r_3 = \frac{\Delta}{s-c}$.Given $2r

Vedclass · Accepted Answer

$4 : 3 : 5$

Vedclass · Answer

(A) We know that the exradii of a triangle are given by $r_1 = \frac{\Delta}{s-a}$,$r_2 = \frac{\Delta}{s-b}$,and $r_3 = \frac{\Delta}{s-c}$.Given $2r_1 = 3r_2 = r_3 = k$ (let).Then $r_1 = \frac{k}{2}$,$r_2 = \frac{k}{3}$,and $r_3 = k$.Thus,$\frac{1}{r_1} = \frac{2}{k}$,$\frac{1}{r_2} = \frac{3}{k}$,and $\frac{1}{r_3} = \frac{1}{k}$.We know that $\frac{1}{r_1} = \frac{s-a}{\Delta}$,$\frac{1}{r_2} = \frac{s-b}{\Delta}$,and $\frac{1}{r_3} = \frac{s-c}{\Delta}$.Summing these,$\frac{1}{r_1} + \frac{1}{r_2} + \frac{1}{r_3} = \frac{3s - (a+b+c)}{\Delta} = \frac{3s - 2s}{\Delta} = \frac{s}{\Delta} = \frac{1}{r}$.Also,$\frac{1}{r_1} + \frac{1}{r_2} + \frac{1}{r_3} = \frac{2}{k} + \frac{3}{k} + \frac{1}{k} = \frac{6}{k} = \frac{1}{r}$,so $r = \frac{k}{6}$.Using $s-a = \frac{\Delta}{r_1} = \frac{\Delta}{k/2} = \frac{2\Delta}{k}$,$s-b = \frac{3\Delta}{k}$,and $s-c = \frac{\Delta}{k}$.Since $s = \frac{6\Delta}{k}$,we have $a = s - (s-a) = \frac{6\Delta}{k} - \frac{2\Delta}{k} = \frac{4\Delta}{k}$,$b = \frac{3\Delta}{k}$,and $c = \frac{5\Delta}{k}$.Therefore,$a : b : c = 4 : 3 : 5$.

In a triangle $ABC$,if $2r_1 = 3r_2 = r_3$,then $a : b : c =$

Similar Questions

With usual notation,in a triangle $ABC$,if $\frac{b+c}{11} = \frac{c+a}{12} = \frac{a+b}{13}$,then the value of $\cos B$ is equal to

In $\triangle ABC$,with usual notations,if $b=3$,$c=8$,and $m\angle A=60^{\circ}$,then the circumradius of the triangle is . . . . . . units.

If $A, B, C$ are the angles of a $\Delta ABC$,then with usual notations,$\frac{c^{2}-a^{2}+b^{2}}{a^{2}-b^{2}+c^{2}} = $

If the sides of a triangle are in $A.P.$,then the cotangents of its half-angles will be in

In a triangle,if $b=20, c=21$ and $\sin A=\frac{3}{5}$,then $a$ is equal to :

Vedclass Test Series

Exam Paper Generator

Online Exam Module